A magnitude 7.2 earthquake bolted past Rosario García González’s house in Baja California on a spring afternoon in 2010. González, an elder of the indigenous Cucapah community, later recounted the remarkable sight to scientists: As the quake cracked open the surface, it kicked up a cloud of dust, like a car racing across the shrubby landscape
But the car, it seemed, was going the wrong way.
Earthquakes usually crack the surface traveling in a single direction, like the tip of a tear through a piece of paper. But according to González, the dust cloud from the progressing quake was rushing back to where the temblor originated—the exact opposite direction scientists expected.
This eye-witness account of a backward-racing quake thrilled scientists. Orlando Teran, who at the time was working toward his Ph.D. at the Ensenada Center for Scientific Research and Higher Education, called the description “spectacular.” But precisely what happened that day remains unconfirmed, because seismic evidence couldn’t verify what González had seen.
Now, an international team of researchers have finally caught one of these “boomerang” quakes in glorious detail, documenting the temblor racing in one direction and then back the way it came.
This magnitude 7.1 earthquake started deep underground, in a gash on the Atlantic seafloor, a little more than 650 miles off the coast of Liberia, in western Africa. It rushed eastward and upward, then did an about-face and boomeranged back along the upper section of the fault at incredible speeds‑so fast it caused the geologic version of...